JPH07116276B2 - Method for producing polyurethane resin - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polyurethane resin composition.

(Problems to be Solved by the Invention) Polyether is often used as a soft segment component of polyurethane resin. Among them, a polyurethane resin using polytetramethylene ether glycol, which is a polymer of tetrahydrofuran (hereinafter referred to as THF), is particularly attractive because it is excellent in elastic properties, low temperature properties, hydrolysis resistance and the like.

However, polytetramethylene ether glycol has a molecular weight of 500 to 4000, which is useful for polyurethane, and has a melting point of 20 to 4
It is in the range of 0 ° C., and crystallization occurs at room temperature or lower temperature, which is a serious problem not only in handling and workability but also in the fields of coating, coating, sealing, etc., which require curing at room temperature. Conventionally, in these fields, a method of adding an appropriate organic solvent has been adopted in order to prevent crystallization, but recently, from the viewpoint of pollution prevention and rationality, a non-solvent system has been aimed at, and polytetramethylene ether glycol is used. It is strongly desired to improve the crystallinity while demanding the above characteristics.

THF / propylene oxide copolyether polyols are known to improve the drawbacks of polytetramethylene ether glycol [Journal of Polymer Science, 58 , 857-8
63 (1962)]. However, since this polyol is a copolymer with propylene oxide, it has a secondary hydroxyl group at the end like polypropylene oxide polyol, its reactivity with isocyanate groups is low, and the physical properties of polyurethane are difficult, and its crystallinity is low. Although it remains liquid at room temperature, it is not satisfactory.

(Means for Solving Problems) The inventors of the present invention have made diligent studies in view of the above circumstances, and as a result, THF
Copolyether polyol obtained by copolymerization reaction of 3-alkyl THF with a molar ratio of 85/15 to 20/80 in the presence of a strong acid catalyst maintains a liquid state at room temperature and is highly reactive with polyisocyanate. The inventors have found that a polyurethane resin composed of the polyol, polyisocyanate, and chain extender has excellent rubber elasticity, and arrived at the present invention.

General formula: (In the formula, _one of R ₁ and R ₂ is hydrogen and the other is a C ₁ -C ₄ alkyl group), 3-methyl THF can be mentioned as a representative example of a 3-alkyl-substituted tetrahydrofuran, which is described in US Pat. 1,4, described by Copelin in No. 3,859,369
-Synthesized by hydroformylation of butenediol and hydrogenation, reduction of itaconic acid and the like. THF
It is known that and 3-methyl THF undergo a copolymerization reaction. The copolyether polyol of the present invention means THF and 3-
The molar mixing ratio with methyl THF is 85/15 to 20/80, and T
Obtained by copolymerizing strong acids capable of ring-opening HF, such as chlorosulfonic acid, fluorosulfonic acid, and perchloric acid, usually at a temperature of 0 ° C to 50 ° C. Holds liquid state. When the THF / 3-methyl THF ratio is made small in the above molar mixing ratio range, the melting point tends to decrease, and therefore the melting point can be freely changed to obtain a copolyether having a melting temperature suitable for the use temperature and purpose. You can When the molar mixing ratio is 20/80 or less, it becomes a copolyether having substantially no melting point, but its glass transition point rises sharply, which is not preferable for the low temperature characteristics of the polyurethane resin. On the other hand, if the molar mixing ratio is 85/15 or more, the melting point rises and the crystallinity increases, which is not suitable for the purpose. From the balance of crystallinity and physical properties of polyurethane resin, a preferred copolyether polyol is obtained. The THF / 3-methyl THF molar mixing ratio is 80.
/ 20 to 30/70.

The above-mentioned copolyether polyol is a colorless transparent liquid at room temperature and has a primary hydroxyl group at the end, so it is highly reactive with isocyanate groups, and the reactivity of polypropylene oxide polyol and THF / propylene oxide copolyether polyol is about 3 to 4 Double. Therefore, even in the field of polyurethane resin, it is suitable for a room temperature curing process and further a reaction injection molding (RIM) process.

The molecular weight of the copolyether polyol used in the present invention is not particularly limited, can be widely used depending on the target polyurethane resin, and is 500 to 5,000, but particularly 800
Nos. 4 to 4500 exhibit the effects of the present invention.

On the other hand, the polyisocyanate compound is a compound having two or more isocyanate groups in the molecule, for example, tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate. Examples thereof include polyisocyanate compounds generally used in the synthesis of polyurethane resins such as naphthylene diisocyanate and hydrogenated diphenylmethane diisocyanate, and these may be used alone or in combination of two or more.

The chain extender is an active hydrogen atom-containing compound that reacts with a terminal isocyanate group of a prepolymer usually used in the production of polyurethanes of this type, and when it is specifically shown,
Compounds with two or more hydroxyl groups and amino groups, such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, xylylene glycol,
Glycerin, trimethylolpropane, ethylenediamine, propylenediamine, phenylenediamine, diaminodiphenylmethane, methylene bis (2-chloroaniline) and the like. Other examples include hydrazine compounds and water. The resin obtained using diamine, hydrazine and water is polyurethane-urea.

The polyurethane resin composition of the present invention comprises, for example, reacting a copolyether polyol compound with a polyisocyanate compound to synthesize an isocyanate group-containing precursor (prepolymer), and then reacting with a chain extender, It can also be obtained by a step method, or by a usual polyurethane resin production method such as a one-shot method in which a copolyether polyol, a polyisocyanate and a chain extender are simultaneously reacted.

In the above synthesis, the reaction temperature varies depending on the process, application, etc., but is generally carried out in the range of 50 to 200 ° C., but in the case of the present invention, the temperature is 50 ° C. or lower because the melting point of the copolyether polyol is low. But the reaction is possible. On the other hand, the composition ratio of each component varies depending on the target polyurethane resin, but the prepolymer needs to contain an isocyanate group, and the isocyanate group of the polyisocyanate compound is 1 or more per 1 equivalent of the hydroxyl group of the copolyether polyol compound, preferably Taken over 1,2. The compounding ratio of the final reaction product is 1 for the isocyanate group in any method.
The total active hydrogen atom equivalents of the copolyether polyol and the chain extension compound are taken to be 0.9 to 1.1 with respect to the equivalent amount.

In the above reaction, a catalyst, a stabilizer and the like can be added if necessary. Examples of the catalyst include triethylamine, tributylamine, dibutyltin dilaurate and stannous octoate, and examples of the stabilizer include ionol (BHT), distearyl thiodipropionate, di-betanaphthylphenylenediamine, tri (dinonyl). Phenyl) phosphite and the like.

The polyurethane resin of the present invention is considerably superior to the physical properties of the polyurethane resin obtained from polypropylene oxide polyol and THF / propylene oxide copolyether polyol which are liquid at room temperature, and is almost the same as the physical properties of the polyurethane resin obtained from polytetramethylene ether polyol. It is an excellent elastic body.

(Example) Next, the present invention will be described in more detail with reference to Examples. The hydroxyl value of the copolyether polyol in the examples (OH value mg K
OH / g) was determined by the pyridine-acetic anhydride method, and the number average molecular weight was determined from this. Composition analysis of 3-methyl THF unit, THF unit, and terminal hydroxyl group analysis are performed by ¹³ C-NMR (JEOL FX-
60), melting point (Tm) and glass transition point (Tg) are based on DSC (Rigaku Denki DSC-8230)
The measurement was performed according to K6301.

Example 1 288.4 g (4 mol) of dehydrated THF and 86.1 g of 3-methyl THF
(1 mol) [molar mixing ratio 80/20] with a stirrer, thermometer, N ₂
The flask was placed in a 1-necked separable flask equipped with a sealing device, and 10.5 g of 70% perchloric acid and 95 g of acetic anhydride were added at a temperature of 10 ° C. to carry out a polymerization reaction for 8 hours. Neutralize the reaction completed liquid with 500 g of 20% sodium hydroxide aqueous solution, follow the general method below to perform monomer recovery, hydrolysis and purification operations, and copolyether glycol 275 g which is a colorless transparent liquid at room temperature.
(Yield 73.4%) was obtained. As a result of NMR analysis, this product had a hydroxyl value of 103.9, a number average molecular weight of 1080, and was found to have only primary hydroxyl groups at the end, and it was a copolyether glycol having a molar composition ratio of THF conit and 3-methyl THF unit of 86/14. As a result of DSC analysis, Tm = 1 ° C. and Tg = −85 ° C.

500c equipped with stirrer, thermometer, N ₂ seal-pressure reduction device
c 100 g of the above-mentioned copolyether glycol was placed in a four-neck separaval flask, vacuum dried at 100 ° C. for 1 hour, dissolved and mixed in 100 g of sufficiently dehydrated dimethylacetamide, and distilled and purified to obtain 4,4′-diphenylmethane diisocyanate ( Known method [J.poly.sci.chem.E]
ds., 13,1657 ('75)] reaction rate constant K ₁ at 30 ℃
When Kg / eg · sec was calculated, K ₁ = 4.3 × 10 ⁻³ was obtained, and THF-propylene oxide copolyether glycol (molecular weight 980, K = 1.2 × 10 ⁻³ ) and polypropylene oxide glycol were measured at the same time. (Molecular weight 1000, K ₁ = 0.9
X10 ^-3 ) was about 4 times.

Next, 200 g of the above copolyether glycol was placed in a similar 500 cc separable flask, vacuum dried at 100 ° C. for 1 hour, 106 g of MDI was added, and reacted at 60 ° C. for 5 hours to obtain a prepolymer (NCO = 6.50%). . Take 150 g of this in a mixer prepared separately, add 10 g of 1,4-butanediol after degassing, mix thoroughly for a few minutes, then preheat 20 cm × 30 cm × 0.2 cm
It was poured into a glass mold and cured in an oven at 110 ° C for 16 hours to obtain a polyurethane sheet. this
The sample was left to stand in a thermostatic chamber at 20 ° C for 1 week and subjected to physical property measurement. The physical properties of the prepolymer and polyurethane are shown in Table-1.

Examples 2-4 and Comparative Examples 1, 2 The molar mixing ratio of THF and 3-methyl THF was 50/50 (Example 2), 30/70 (Example 3), 90/10 (Comparative Example 1), 10/90
(Comparative Example 2), Copolyether obtained in the same manner as in Example 1 except that the ratio was set to 80/20 (molecular weight 2000, Example 4) and the amount of perchloric acid / acetic anhydride was changed to match the target molecular weight. Physical properties of glycol and polyurethane are shown in Table-1.

Comparative Examples 3 and 4 Commercially available polytetramethylene ether glycol (PTG,
Table 1 shows the molecular weight of 1020), THF / propylene oxide (30% by weight) copolyether glycol (PPTG, molecular weight of 980) obtained by a known method, and the physical properties of the polyurethane obtained in the same manner as in Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Haruo Watanabe 7-43, Oguro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Hodogaya Chemical Industry Co., Ltd. Central Research Laboratory Tsurumi Branch Office (72) Inventor Shuichi Takeuchi Yokohama-shi, Kanagawa 7-43, Daikoku-cho, Tsurumi-ku, Tsurumi Branch, Central Research Laboratory, Hodogaya Chemical Co., Ltd. (56) Reference JP-A-57-202320 (JP, A)

Claims (1)

[Claims] 1. Reacting a copolyether polyol, a polyisocyanate compound and a chain extender obtained by copolymerizing tetrahydrofuran and 3-alkyltetrahydrofuran at a molar ratio of 85/15 to 20/80. A method for producing a polyurethane resin, comprising: